MONDAY, May 20 (HealthDay News) -- Obese and overweight men and women who suffer from heartburn often report relief when they lose weight, a new study shows.

The researchers tracked the effects of weight loss over a year in patients who had a persistent form of heartburn known as gastroesophageal reflux, or GERD.

"If you lose weight, you will have improvements in your reflux symptoms," said study author Dr. Preetika Sinh, a gastroenterology fellow at the University of Kansas School of Medicine. In women, but not men, long-term exercise also helped reduce symptoms, she added.

Sinh was scheduled to present the findings Monday at the Digestive Disease Week annual meeting in Orlando, Fla.

Previous research also has linked weight loss with a decline in GERD symptoms.

Heartburn, or acid indigestion, is very common, with more than 60 million Americans having it at least once a month, according to the American College of Gastroenterology. Stomach acid flows backward up into the esophagus, and the burn begins.

GERD, the more frequent, chronic form of heartburn, can lead to complications if left untreated, including a narrowing of the esophagus or precancerous changes in the esophageal lining.

Sinh evaluated more than 200 men and women with an average age of 46. At the start of the study, all were overweight or obese, with an average weight of 220 pounds.

At the beginning of the study, 38 percent had heartburn scores severe enough to be classified as GERD. After six months, the patients' average weight decreased to 183 pounds, and only 16 percent still had GERD.

During the next six months, 172 of the patients regained weight, and the percentage of those with heartburn increased again, from 16 percent to 22 percent. Even a small amount of weight gain -- less than 5 percent of their initial weight -- led to worsening symptoms, Sinh found.

Sinh then focused on the 41 patients who didn't regain their weight and found that the percentage with heartburn continued to decline and the symptoms continued to improve.

As part of the weight-loss program, the patients were told to aim for five hours a week of moderate activity such as walking or jogging. The average amount logged was a little less than four hours, Sinh said.

In women, but not men, the exercise also helped to improve heartburn.

Sinh said she can't explain the mechanisms behind either the weight loss or the exercise, or why the exercise seemed to help only women. Although the study found a link between weight loss, exercise and GERD, it did not establish a cause-and-effect relationship.

While the use of heartburn medications is common, Sinh said she can't say if the men and women improved enough to go off medication, since she didn't track those results. Only about 5 percent of the men and women were on heartburn medications in the first place, she said.

One expert said the study had some strengths.

To start with, a relatively large number of people were studied, said Dr. Lauren Gerson, an associate professor of medicine and gastroenterology at Stanford University School of Medicine.

Besides just asking patients to report symptoms, she said, "it would be useful to have pH studies [done to evaluate GERD] to document improvement in overall pH scores after weight loss."

Even so, she said, the findings echo those of an even larger study, published in 2006, that found that weight gain -- even in those with normal weight -- was linked to new heartburn symptoms and weight reduction was linked to a decline in symptoms.